Service-Oriented Architecure (SOA), Rich Internet Applications (RIA), and Asynchronous Java and eXtended Markup Language (Ajax) comprise the backbone behind now-widespread Web 2.0 applications, such as MySpace, Google Maps, Flickr, and Live.com. Although these robust tools make next-generation Web applications possible, they also add new security concerns to the fi eld of Web application security. Yamanner-, Sammy-, and Spaceflash-type worms are exploiting client-side Ajax frameworks, providing new avenues of attack, and compromising confidential information. Portals such as Google, Netflix, Yahoo, and MySpace have witnessed new vulnerabilities recently, and these vulnerabilities can be leveraged by attackers to perform phishing, cross-site scripting...